A new X-ray technique that gives clearer images of cartilage and joints could help doctors diagnose osteoarthritis.

The most common form of arthritis, it affects more than seven million Britons - usually the middle-aged and elderly.

Osteoarthritis is caused by the degeneration of the cartilage - the protective material that stops bones rubbing together in the joints.

And the new diffraction enhanced imaging (DEI) technique produces images with greater contrast to highlight the cartilage and help doctors identify the degenerative disease.

This could be an important new tool for diagnosing osteoarthritis much earlier in the disease cycle

Dean Chapman, research co-ordinator

Conventional X-ray diagnosis of osteoarthritis indicates only the extent to which bones converge as the cartilage deteriorates.

Dean Chapman, who led the United States research team, said: "Since cartilage is a tissue that cannot be imaged by conventional radiography, this could be an important new tool for diagnosing osteoarthritis much earlier in the disease cycle."

The disease, which causes severe disability and pain, develops in the joints of the neck, lower back, knees, hips, fingers and others that have been injured or subjected to prolonged heavy use.

According to estimates, 60% of 65-year-olds have moderate to severe osteoarthritis in at least one joint.

Drug development

The Arthritis Research Campaign has welcomed the development.

Dr Madeleine Devey said treatments were currently prescribed on the basis of "how the patient feels, which is highly subjective and not easy to measure".

The technique is at a very early stage of development and will require a lot more testing and validation

Dr Madeleine Devey

"This appears to be a very interesting new approach," she said.

But Dr Devey warned: "The technique is at a very early stage of development and will require a lot more testing and validation."

DEI could also allow pharmaceutical companies to test experimental drugs throughout the course of the disease process.

They currently induce osteoarthritis in animals before treating them with drugs and examining their cartilage at post-mortem.

Details of DEI appear in the March issue of the journal Osteoarthritis and Cartilage.